Interlibrary lending and document delivery have become an integral part of the services that contemporary libraries offer. The copyright laws in most countries authorized this copying within reasonable limits, but tensions with publishers may be growing. For interlibrary services to remain effective, libraries must continue to lobby politicians to defend their legal basis. Libraries must also continue to work with publishers to address legitimate economic concerns. This paper looks at the legal basis for interlibrary services, particularly document delivery, in the US, Canadian, and German law.